Our Verdict

The Feathered Friends Vireo UL is a specialty bag that is designed for use while alpine climbing. With this goal in mind, this hoodless mummy completely cuts out the zipper to save weight and bulk, and while it has a temperature rating of 25F for the lower body, it uses less down fill on the upper body, which is rated to 45F. The idea is that you will pair it with your insulated belay jacket, which you have to carry on the climb with you anyway, to again save weight and keep you warm during your bivy. At 16.4 ounces, it is indeed very light. While it will serve one well as an alpine climbing sleeping bag, we also found it to be comfortable and enjoyable for use while backpacking as well. The 62" version we tested in our updated review weighs in at 13.9 ounces! The longer 68" version we previously tested also weighed in at less than 16 ounces. We recommend the Top Pick Award winner Vireo to alpinists and cold weather adventurers who climb or hike with a very warm winter parka.

For the majority of ultralight backpackers and thru-hikers, we recommend a quilt for warmth and versatility. For both of those capabilities at a low price, the Enlightened Equipment Revelation 20 fully-opening quilt is one of our top scoring models overall and has a relatively modest price tag.

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Our Analysis and Test Results

The Vireo UL is unique in that it has a few different design elements not found on any other sleeping bag in this review. It is the only mummy bag to forego the use of a zipper, which we somewhat lamented. No zipper meant this bag is not easy to get in or out of (can you say wriggle?), and for a bag that is designed for climbing, creates quite a conundrum as to the best way to stay tied in. Well, there is no debate, the only way to stay tied in is to run the cord out the top of this bag, but we find this to be annoying and less than ideal. In our opinion, the two-way zipper used on the Patagonia 850 Down Sleeping Bag 30 is far more practical as a way to manage the tie-in point while on a wall or bivy on a mountain, while also adding versatility to ventilate.

What we did like was the unique variable fill: the bottom half of the bag is rated to 25F, and the top half to 45F. The idea is to use an insulated jacket that you must carry anyway to keep you warm at night. Because it is meant to be paired with a bulky jacket, the fit in the torso is the most spacious of any mummy bag we tested, and on warm nights you can always sleep in this bag without the belay jacket. That's what we did most of the time when using it for backpacking, and we simply loved the extra space.

Where to Find It
Feathered Friends products are not sold at major online retailers. Go directly to their website to purchase:FeatheredFriends.com.

Performance Comparison

Waking up to a chilly morning after sleeping out in the San Juan Mountains. The Vireo, in blue, and the HighLite in purple.

Warmth

As we have mentioned many times already, the Vireo UL has a variable fill of 25F on the lower body and 45F on the upper body. To be honest, observing from the outside, it is hard to discern the difference in lofting insulation between the two halves. To accomplish this, Feathered Friends uses 9.4 ounces of 950+ fill goose down, which is amongst the highest rated down of any bag we tested. The baffles are horizontally oriented, rather wide, and sewn through. Unfortunately, we noticed that down seems to be able to move around quite freely in these large and wide baffles, and toward the end of our testing period, we noticed that a few total dead spots had developed where the down had migrated out of a certain area, leaving it devoid of insulation.

The Vireo is designed to be paired with a warm jacket to take advantage of clothing you already have with you. With this idea in mind, it uses less insulation on the upper half than on the lower half, which is rated to 25F. We liked how the torso region of this bag was super spacious to fit our extra clothes.

Weight

We tested a 74 inch long Vireo UL, which is the longest size that they make. Our test model weighed in at 16.4 ounces, slightly lighter than the advertised 16.7 ounces, and the included stuff sack weighed an additional 0.8 ounces. This made it the third lightest sleeping bag in our test, behind only the Sea to Summit Spark I and the Western Mountaineering HighLite. Of these three lightest bags, there is no doubt that this one slept the warmest, and also had the most spacious fit.

The Vireo UL packs down relatively small into its included yellow stuff sack. At 16.4 ounces, it was also the third lightest sleeping bag in our review.

Comfort

Since this is a hoodless mummy bag that is only meant to come up over the shoulders while being worn, the size choices are a bit short compared to most that we tested. For this test, we purchased a 74-inch bag, which was the longest option (it also comes in a 62-inch option). This length easily fit our head tester's 5'11" frame, comfortably coming over the top of the shoulders. While the legs and feet of this bag are quite narrow, the torso and upper body region are the widest and most spacious of any mummy bag tested, significantly adding to how comfortable we felt. When we didn't wear an extra jacket inside, this bag felt downright palatial! Even with the down jacket on, as it is designed to be used, the upper body is not too restricting.

We ordered a 74" version of the Vireo, which was the longest that they had. It fit our 5'11" head tester nicely, easily covering his shoulders. The hood on his down jacket helped keep his head warm throughout the night.

Comparing and testing mummy bags in the Bighorn Mountains of Wyoming, we found that the Vireo had by far the most spacious fit through the torso, and was also really light!

Versatility

With no zipper or enclosure system of any sort, this bag suffers in the versatility department. Not only is it a pain to wriggle in and out of, but it is literally impossible to ventilate on a warm night to let out some of the built up heat. Used in the mountain setting as it is designed to, this shouldn't be a problem, but if you intend to stretch this bag's usage to camping at the base of a mountain, or a simple backpacking trip, then it's a tad annoying.

The variable fill of this bag does add to the versatility a bit, as you always have the option of wearing an insulated jacket on cold nights, or foregoing any extra layers on warm nights. We also liked how the outer shell fabric is made of naturally water-resistant Pertex Endurance UL fabric, lessening the chances of water being an issue in the mountains. It still ranked near the bottom though, roughly the same in our minds as the Western Mountaineering HighLite.

Chad Kellog in the Feathered Friends Vireo sleeping bag in the Picket Range, Washington. Our Top Pick for Alpine Climbing is designed for use with warm upper layers and works well for sleeping sitting up.

Features

With very few features, there is not a whole lot to talk about here. The only feature that hasn't already been discussed is the single drawcord and buckle on the collar. We liked how the cord is made of static cord, as opposed to stretchy bungee cord, and the buckle does a fine job of holding the cord tight. Like many of the other bags, we still had the complaint that the long cord, when fully tightened, dangles in one's face and near the neck. Regardless, this bag scored just below the Zpacks Classic, which included a ¾ length zipper, and the Sea to Summit Spark I, which added a hood and zipper, at a lighter weight.

Pretty much the only feature to speak of on this zipper-less mummy bag was the single draw cord around the neck opening. It worked just fine.

Best Applications

According to Feathered Friends, this bag is designed specifically for alpine climbing adventures, where weight is of critical importance. We agree with them that this will be the best use of this bag, but we found that it works really well also for ultralight backpacking, and its design makes it a decent choice for the cooler spring and fall seasons. It would not make an ideal choice for warm summer trips unless you are in the high mountains.

Drying out your down sleeping bag in the morning after it gets moist from condensation inside the tent is essential on long backpacking trips to keep the down lofting as much as it can.

Value

Retailing for $349 for the 74" bag, the Vireo UL is about average when it comes to price. You can get the 62" for $309 or the 68" length for $329. While we think the craftsmanship of this bag is excellent, ensuring that you get what you pay for, we have to concede that the design is a bit quirky, and probably is not ideal for very many people. Unless you are going alpine climbing and you don't mind the inconvenience of staying tied in while in this bag, we wouldn't recommend spending this much money for the Vireo UL.

Conclusion

The Feathered Friends Vireo UL is a specialty bag designed with alpine climbing in mind. Its variable fill is meant to take advantage of the insulation you are already carrying with you in the form of a belay parka, thereby saving weight. With no zipper at all, entering and exiting this bag is best described as awkward, and we aren't sold on the idea of needing to run our tie-in cord down through the top of our bag while bivying. That said, its very spacious fit was among the most comfortable we tested, and it is an adequate lightweight bag for backpacking during the shoulder seasons, not just while alpine climbing.